The present invention relates to the field of ovens for preparing food. More particularly, the invention relates to the field of ovens for baking pizza.
Historically, pizzas have been baked in deck ovens for a time sufficient to bake the crust and to bake, heat, and/or melt the ingredients atop the crust. Typically, the required bake times would be between 15 and 25 minutes per pizza.
One improvement to the art of baking pizzas has been the development of the conveyor oven. Through the use of conveyor ovens, it has been possible to improve the consistency of baking, ease of operation and utilization of available floor space. Thus, conveyor ovens have become the industry standard for high volume pizza restaurants and pizza delivery systems.
Another improvement has been the development of impingement ovens for baking pizza. These ovens, which are a special type of forced convection oven using columnated heated air to impact the pizza, have increased heat transfer capabilities and therefore have reduced the bake time significantly. One example of such an impingement oven is described in U.S. Pat. No. 4,679,542 to Don Paul Smith.
These impingement ovens have achieved wide acceptance among pizza restaurants, and pizza delivery systems, especially those which deal with high volume and/or fast service. The typical bake time for the commercially available impingement ovens is in the range of 5 to 9 minutes.
U.S. Pat. No. 4,632,836, to Abbott et al. and assigned to the same assignee as the present application, describes a pizza preparation and delivery system which is designed to deliver restaurant quality pizzas to the consumer's home or place of business. The entire disclosure of this '836 patent is incorporated herein by reference. The system described in this patent includes vehicles which were not only adapted to deliver the pizza, but also adapted to assemble and bake the pizza while in transit. Each vehicle in this system was equipped with a refrigerated case for storing pizza shells, a preparation station with pizza toppings to create an assembled pizza, and a conveyor oven for baking the assembled pizza.
The vehicles used in the preferred embodiment described in the '836 patent were modified FORD E-350 trucks with a van type body mounted thereon. Each vehicle included a driver's station and a kitchen area. A cook's chair was put in the kitchen area and the vehicle was laid out so that, while seated in the cook's chair, the cook could reach the pizza assembly station, the oven, and the cutting table. A door was provided in the side of the van for the cook to exit the vehicle and deliver the pizza to the door of the customer. Preferably, the vehicle of the '836 patent would be manned by a driver and a cook so that the driver could drive and the cook could remain in the cook's chair to assemble, cook, box and cut pizzas. Naturally, when the vehicle of the '836 was manned by a single worker, the driver would have to find a place to park the vehicle while he moved back to the kitchen area to prepare pizzas to be cooked. Also, the lone operator would have to park in order to remove the cooked pizza from the oven.
U.S. Pat. No. 4,556,046, to Riffel et al. and also assigned to the assignee of the present invention, described an improved ventilation system for a pizza preparation and delivery vehicle such as that described in the '836 patent. The entire disclosure of the '046 patent is also incorporated herein by reference.
Although the pizza preparation and delivery system described in the '836 and '046 patents enjoyed a measure of success, it was found that the purchase, operating, and maintenance costs of the relatively large vehicles used in the preferred embodiment ran higher than what was desirable.
One factor adding to these costs was the gasoline or propane electric power generator which was included on the vehicles to supply the power needs of the refrigerated cases and ovens on the vehicles. Not only did this generator add to the purchase, operating, and maintenance costs of the vehicle, it also increased vehicle noise.
U.S. Pat. No. 4,643,167, to Brewer and also assigned to the assignee of the present invention, described a further improvement to the ventilation system for an oven within a pizza preparation and delivery vehicle. By the time the application for the '167 patent was filed, the preferred vehicle had been downsized to a typical full-size van, such as the FORD "Econoline". The kitchen layout was the same in the '167 patent as in the '836 and '046. That is, the new vehicle included a driver's station and a kitchen area with a cook's chair and a conveyor oven. The new vehicle also included a separate electrical generator.
Although using this smaller van resulted in a reduction of the purchase, operating, and maintenance costs, market pressures still motivated the search for a vehicle that would be less expensive to purchase, operate and maintain. In particular, it is critical to minimize the costs of this new mobile preparation and delivery system so that an operator can offer pizza at the competitive prices, while achieving the same or higher profit levels as one could achieve in a conventional pizza restaurant or delivery business.
Co-pending U.S. patent application Ser. No. 07/258,969 (Attorney Docket No. 106-060) describes a compact pizza preparation and delivery vehicle which has solved some of the problems mentioned above. In particular, a vehicle which is less costly to purchase, operate, and maintain is described therein. One feature of the described embodiment is that the overall vehicle is much smaller in size. Another feature is that the vehicle does not require a separate generator to supply electrical power to the equipment on the vehicle.
One of the challenges in the development of the described vehicle was that of providing a pizza oven that would be small enough, light enough, and have a low enough electrical power demand to meet the specifications dictated by this new compact vehicle.